Well that went from zero to Princest awfully fast.

7516630
Man, I thought that mention from the guard that Celestia went into a closet with a rope ten minutes ago was just a really dark joke, then BAM!

Also, I'd reread that scene @ author. When she leaves her room, entering abrupt conversation is a massive cutoff. I'd add a description there, as well as entering into Celestia's, uh, closet?

7516630 I had to sit up and get closer to the screen to find out what the hell went down.

7517554 yeah, having so little context realy doesnt help trying to piece everything together.

The kind of vibe I'm getting from the fact that she threw the tiara is that she doesn't want to be royalty anymore, I don't know but that's what I'm getting.

Seems i missed a few tags when i started reading this. Well, i never quit a story i start........ I guess i'll see how this goes.

Celestia narrowed her eyes, before flopping back and curling herself up. She grabbed her large nipple with her mouth, and took a comforting drink of milk as she cursed Luna for bringing up a mistake she made… A small harumph could be heard from her as her ass pointed straight at Luna, it’s sheer size making the rest of her unable to be seen from this angle. Her pussy was also on display though, and visibly moist. “No, sister, I wasn’t practicing. I thought we could roleplay tonight. You know, spice up bonding time.”

static.fjcdn.com/pictures/That+escalated+quickly+remix+of+the+post+that+i+found_9eabc9_4089753.jpg

Jesus Christ man....

Huh.
While there isn't anything that is a complete deal breaker, the whole chapter is so chaotic and random, with completely unrelated scenes not separated.
Otherwise the writing is good ^^
Just some constructive criticism :)

Looks like Celestia has learned squat about sibling interaction after being away from her sister for 1000 years.